On Wednesday, when one woman paid for her order at a Starbucks drive-through–and the order of the stranger behind her–she started a chain of kindness that would continue on for 11 hours and nearly 400 people.

The woman who started the whole chain simply asked her barista at the window, 29-year-old Vu Nguyen, to charge her for the iced coffee she ordered and the caramel macchiato for the person behind her. When the next driver pulled up to the window, Nguyen explained what the first customer did and the chain was born.

Another patron, Tim Burnside, said he participated in the chain that morning and returned in the afternoon to see if it was still going on. When he saw it was alive and well, he ordered a second drink. “It’s nice just to do a random act of kindness for someone you don’t know,” he said.

Nguyen and his fellow baristas kept a running tally of the customers who had paid it forward and by 1:30 p.m., found that it had reached 260 orders.

While the chain didn’t last until closing time at 10 p.m., it had a good run up until 6 p.m. when a customer ordered a regular coffee, but declined to pay for the customer behind her. Nguyen told the paper that he believed she didn’t fully understand the concept of the chain.

And with that, the act of paying it forward at the Starbucks drive-through line touched 378 people. Had it lasted until closing time, baristas said they would have tried to find a way to keep it going the following morning.